The present invention relates to part metal containers for cosmetic preparations, such as lipstick and mascara. Such containers are generally tubular and may contain an applicator, in the case of mascara, or a raise/lower mechanism, in the case of lipstick.
At one time, such containers were all metal but more recently, plastic has become the material most commonly used in their manufacture. Plastic components have many advantages. For example, they can be easily and cheaply moulded in complex shapes, they provide a smoother engagement with less noise than metal components and the plastics composition can be modified to provide certain barrier properties. However, consumers prefer the weight and feel of metal components and associate these characteristics with quality and durability. Hence, it is desirable to provide a plastics container having the look and feel of a metal component.
Several methods have been used to provide plastics containers which have the external appearance of a metal container. Such methods include electroplating the external surfaces of the plastics container with a thin metal layer. The disadvantage of this method is that the container has the appearance of a metal container but does not have the weight or feel of a metal component.
Alternatively, a pressed metal shroud may be provided around the external surface of a moulded plastics container. The plastic component is housed inside the metal shroud. This arrangement combines the advantages of producing the container from a plastics material, whilst the external metal shroud provides the appearance of a metal component. The metal shroud also improves the weight and feel of the container. However, the metal forming and stamping process requires a large investment in machinery and tooling. Transfer presses are required, having between 4 and 12 stages. During each stage the final shape of the component is progressively formed, starting from a thin sheet of metal. Once the metal shroud has been formed, a surface finish is then applied to the external surface of the shroud, for example varnish or paint.
The aim of the present invention is to provide an improved method of manufacture for all or part of a tubular cosmetic container, having the look and feel of a metal component. The method according to the invention requires simpler machinery and tooling than the prior art and therefore lower capital investment than that currently needed to produce pressed metal shrouds.
Accordingly, the invention provides a method of manufacture for tubular cosmetic containers, each container having at least one plastics part and a metal sleeve, comprising the steps of:
i. Extruding a metal tube having the desired cross section,
ii cutting the metal tube into lengths to produce a plurality of metal sleeves, and
iii. arranging at least one moulded plastics part in each of the metal sleeves.
The method of manufacture according to the invention uses an extrusion process to form the metal part of the container. The extrusion process is a one-step process requiring much simpler and cheaper equipment than the multi-stage presses needed to produce conventional pressed shrouds. A metal blank of suitable size and shape is input into the extruder. The extruder produces a long, extruded tube of the required cross sectional shape, in a single process step. The extrusion technique can be used to produce a wide variety of cross sectional shapes by use of a suitably shaped die. Hence, the extruded metal shroud may have a more complex profile than that which can currently be produced using pressing techniques.
Furthermore, due to the multi-stage forming of pressed metal shrouds, thin metal plate is used as the starting material for the pressing process. Hence, the final pressed component is relatively thin. On the contrary, the extrusion process can be used to produce a tube having a much greater wall thickness. This has the advantage that the extruded tube will be more robust than an equivalent pressed shroud and thereby less prone to damage. Furthermore, use of a thicker metal shroud improves the weight and feel of the component.
Preferably, a metal blank of suitable material is heated to a temperature just below that at which the material begins to soften. The heated metal blank is fed into the extruder and a long, thin, extruded metal tube (of approximately 30 to 50 metres in length) is emitted. As it is pushed out of the extruder, the extruded tube tends to curve and snake. Thus, the extruded tube is preferably stretched as it leaves the extruder, to straighten it. The stretching process is preferably carried out when the material is almost cold. The extruded tube may then be cut into the required lengths to make shrouds for a number of cosmetic containers.
Advantageously, where a surface finish is required, the surface treatment is applied to the extruded tube before it is cut into shorter lengths. Numerous surface finishes can be applied including, brushed, anodised, varnished, lacquered and painted. The surface finish is much simpler and easier to apply to the long tube lengths than to discrete components, which have to be handled individually and loaded into trays for application of the surface finish. Hence, a large number of finished, extruded, metal shrouds can be produced cheaply and with less labour than that currently required to produce conventional finished, pressed components.
The cosmetic container further comprises an end, which is held captive in the extruded metal tube. The end may be made from metal or a plastics material and may have the same external appearance as the extruded tube. Where a metal finish is required, a plastics end may be electroplated. This is a much simpler process than that required to electroplate the whole of a plastics cosmetic container. Only one side of the ends needs to be coated, therefore, the ends can simply be arranged in a tray for electroplating. When electroplating a conventional plastic cosmetic container, the whole external surface of the container needs to be coated. Therefore, the containers are usually suspended to ensure complete coverage of the thin metal layer.
Where the container comprises a body and a lid, both comprising extruded metal sleeves, the container preferably comprises a plastics insert to ensure smooth engagement of the components during assembly and smooth, quiet use of the container by the consumer. The plastics insert may be provided as a separate component in addition to the end. Alternatively, the plastics insert may be adapted to provide both a smooth engagement surface and an end for the extruded metal sleeve.
The plastics component/s may be moulded separately and retained in the extruded metal tube using known techniques, for example adhesives, a snap fit arrangement or an interference fit. Alternatively, the plastics component/s may be moulded directly inside the extruded tube, thereby eliminating the need for an additional assembly step.
Where the tubular container is used to hold pomades, such as lipstick, the plastics part/s may be adapted to retain or form part of a raise/lower mechanism.
Containers for liquid cosmetics, such as mascara, lip gloss etc. conventionally comprise a lid and a body. The body takes the form of a bottle, to hold the liquid cosmetics, and the lid is adapted to hold an applicator. In accordance with the invention, such containers may comprise a lid having an extruded metal sleeve, an end and a plastics insert adapted to provide or retain the applicator. The body may be provided by a conventional bottle. However, advantageously, the body is also encased in an extruded metal sleeve.
Metal has good barrier properties and this makes the container particularly suitable for storing newer cosmetics compounds, which are often volatile. At present, known barrier cosmetic containers are manufactured from PVC and have thick walls, to provide the necessary barrier properties. However, PVC is banned in many countries. A cosmetic container comprising an extruded metal sleeve encasing a bottle having a thick base but thinner side-walls, will have good barrier properties, without the problems associated with PVC or the requirement for thicker walled containers, which are both costly to produce and more bulky.
Using conventional pressing techniques, it is not possible to produce a metal shroud for conventional cosmetic containers for mascara, for example. The height of the shroud is limited because the pressing technique requires metal to be drawn from the base into the sidewall to provide the height for the shroud. Conversely, using an extrusion process, a long tube can be extruded of the required diameter and this tube can then be cut into any desired length to produce a suitable metal sleeve. Thus, the method according to the invention allows the manufacture of cosmetic containers having any diameter to height ratio required.
The extrusion process may also be used to define a longitudinal groove or rib on the internal surface of the metal sleeve. The internal groove or rib may be used to align the various components of the cosmetic container, for example a lid and a body, and is particularly useful where the external surface of the extruded tube has a complex shape or where a design is applied to the external surface of the tube.
Typically, cosmetic containers according to the invention, are manufactured in an in-line process starting with extrusion of the metal tube and finishing thereof and progressing to full automatic assembly of the metal and plastics parts. Obviously, the plastics parts may be moulded independently of the in-line process. However, where the plastics parts are moulded in-situ inside the extruded tube, the moulding process preferably forms part of the in-line process.
Preferably the extruded metal tube is made of aluminium. The plastics material for the insert is chosen to have the required specification in terms of flexibility, roughness and slide coefficient. Preferably, the plastics insert is moulded from polyethylene or polypropylene.